From: "Naudts, Guido" <guido.naudts@just.fgov.be>
Subject: Re: Question on OWL tests
Date: Wed, 19 May 2004 13:36:52 +0200
> I've done some research on the internet, without any results. Could
> anybody tell me what exactly are the OWL comprehension rules? And why do
> they impede the introduction of a concept in the conclusions?
> (If I missed something important in the standard documents, please
> accept my apology).
> Thanks, Guido
I quick search in OWL S&AS
http://www.w3.org/TR/owl-semantics/semantics-all.html
for ``comprehension'' provides a table of the Comprehension conditions
(principles) in OWL.
They are needed, for example, so that
ex:a rdf:type ex:b .
ex:a rdf:type ex:c .
OWL-entails
ex:a rdf:type _:d .
_:d owl:intersectionOf _:l1 .
_:l1 rdf:first ex:b .
_:l1 rdf:rest _:l2 .
_:l2 rdf:first ex:c .
_:l2 rdf:rest rdf:nil .
Without the first comprehension principle this entailment would not hold
because
ex:a rdf:type ex:b .
ex:a rdf:type ex:c .
would not OWL-entail
_:l1 rdf:first ex:b .
_:l1 rdf:rest _:l2 .
_:l2 rdf:first ex:c .
_:l2 rdf:rest rdf:nil .
i.e., there would not need to be a list containing ex:a and ex:b so there
would be no way to form its intersection.
Yes, this is all an artifact of having to encode OWL syntax in
semantically-meaningful RDF triples.
Peter F. Patel-Schneider
Bell Labs Research